Posts Tagged ‘CCNA. CCDA’

I see a lot of confusion about the Type-4 LSA and what it does. This confusion is high in the CCNA world because little is explained about it and one might think it is useless; however, this is valuable when you’re learning or doing route redistributing into OSPF using External type-2 redistributed routes with multple ASBRs redistributing the same external routes. Read more… Read the rest of this entry »

I get this a lot in my field “I cannot ping the server, it must be down or a network issue”; however, I can log in and telnet to the machine and even RDP/SSH into the machine. Why is this? Simple, the machine is not responding to ICMP ECHO REQUESTS which is default behavior for some systems. Windows 7 and Windows server 2008 DO NOT respond to ping by default because their internal firewalls are set to NOT respond to ICMP ECHO REQUESTS. Therefore, the machine could show as DOWN because it doesn’t respond to ping but the machine could actually be alive and on the network.

I personally recommend allowing your machines to respond to ping because there are no benefits to not allowing it other than confusion that could arise from the unexpected. Hiding a PING response doesn’t provide more security because a TCP SYN scan could prove that your machine is alive and well if there are listening ports, among other methods of host discovery.

To put it simple, DO NOT RELY ON PING as a method of testing connectivity only.